Conventionally, in this kind of hair clipper blade block, a pressing spring which serves to press a movable blade against a fixed blade is normally held in a blade base by fitting bosses provided inside the blade base to boss-holes formed at end portions of the pressing spring and then upsetting or deforming exposed free ends of the boss by cold or hot working. There is also known an alternative method of press fitting a pressing spring to groove portions provided in a blade base (see, e.g., Japanese Patent Laid-open Application No. 10-235036).
In case the pressing spring is fixed by upsetting the bosses as in the prior art, the pressing spring may be retained in a floating state (i.e., the boss holes of the pressing spring may be movable along the axial directions of the bosses) due to processing errors generated by the upsetting process. Further, the reaction force of the pressing spring acts on the deformed bosses all the time. Therefore, if the hair clipper is exposed to elevated temperatures while being circulated in the market or while being used, the deformed bosses may undergo creep deformation and thus the pressing spring may often suffers from floating. This holds true in case of the prior art example in which the pressing spring is press fitted to the groove portions provided in the blade base.
For the reasons noted above, the pressing force of the pressing spring is weak in the prior art hair clipper, which reduces the contact pressure between the fixed blade and the movable blade and thus leaves a gap between the edge portions of the comb-shaped movable and fixed blades. This poses a problem in that the cutting performance of the blade block is impaired and the lifespan of the blade block is reduced depending on the environment in which the hair clipper is used.